Empirical Evidence
by Lys ap Adin
Summary: Riko is an empiricist born, and Hyuuga is pretty sure that she and Kiyoshi are gonna end up killing him. But what a way to go. Riko x Kiyoshi x Hyuuga, adult for smut.


**Title:** Empirical Evidence  
**Characters/Pairings:** Riko/Kiyoshi/Hyuuga  
**Summary:** Riko is an empiricist born, and Hyuuga is pretty sure that she and Kiyoshi are gonna end up killing him. (But what a way to go.)  
**Notes:** Adult for smut. In my head, this is future-fic, somewhere in the college years. 1450 words.

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**Empirical Evidence**

"I still don't see how that could be that much fun," Riko says. "I don't care how much lube you use."

"Trust me," Teppei says with that easy grin that always spells trouble. "It's _great_ if you're doing it right."

Riko tilts her head to the side, a considering light in her eyes, and Junpei knows what's coming before she even opens her mouth to say, "Oh, yeah? Prove it."

He swears Teppei and Riko are going to be the death of him yet.

Teppei is fundamentally incapable of backing down from a challenge, even more so than Riko is, so he's already grinning at her, on the verge of saying something stupid that will mean no one can call a halt to things without losing face. It's up to Junpei to provide the sanity—why does it always have to be him, he wonders, resignedly—and so he says, "Don't forget that there are some basic anatomical differences in play."

"Well, yes, of course, but that doesn't mean that it can't still feel good," Riko says, sparking a delighted laugh out of Teppei. "Thirty percent of all the straight women in the world can't possibly be that long-suffering."

Junpei covers his eyes. Of _course_ she researched it before ever raising the topic. It's Riko. He really should have known.

"You are amazing." Teppei's voice throbs with sincerity; Junpei doesn't have to be looking to know that Teppei's looking at Riko with nothing but wonder and delight in his eyes, like he can't believe there's anything so wonderful in the world as her, or his own luck in getting to behold it. (Junpei would rather start destroying his carefully rebuilt collection of Sengoku figures again than admit it out loud, but that does seem to be pretty much exactly the right way to look at her.)

She knows it, too. "Of course I am." When Junpei takes his hands from his eyes, Teppei has reached for her, setting those large hands of his on her hips and pulling her in close, and she has settled herself over Teppei's lap. It puts her at the right height to fold her hands around Teppei's face and kiss him, which she is doing. Junpei forgets to be trepidatious about her latest schemes because he's too busy watching them instead, the way Teppei's body frames Riko's slender figure—how can she be so tiny, where does she _fit_ all that personality and determination? Junpei has never been able to figure it out—and the way their mouths fit together as they kiss, slow as a summer afternoon.

He's so lost in his reverie, watching the two of them, that when Riko lifts her head and asks, voice gone deeper, throatier, "So what do you say, Jun-chan?" he says "Yes, of course," before remembering what it is he's saying yes to.

Teppei beams at them both. "This is going to be _amazing_."

Junpei just slaps his forehead as he realizes that he's fallen for one of Riko's ploys again.

Not that he really minds doing that, he thinks a little while later, resting against the pillows, slick with sweat and holding Riko against his chest. This way he gets to listen to the soft, breathless sounds she's making, little hitches and bobbles in the way she breathes, small gasps and moans and every once in a while, a tiny little whimper that reaches down somewhere inside Junpei, seizes hold of him, and _twists_.

He doesn't know whether it's better or worse that he can't—quite—see what it is Teppei is doing, because that leaves him to imagine all the possibilities instead. Junpei has a rather good imagination, one fueled by a great deal of empirical evidence for just how very good Teppei is with his hands.

Not that Junpei is a passive bystander for this. "You," Riko had announced right at the start of things, while they were still getting naked, "You, Jun-chan, are going to be responsible for helping my body create favorable associations for this new experience." She'd delivered it with all the expertise of the physical trainer she is, and is studying to be, not that Junpei would have argued with her regardless.

In practical terms, _creating favorable associations_ turns out to mean that Junpei has spent the past little while—it has to have been an eon, an eternity, enough time for civilizations to rise and fall and be forgotten—with his hands on Riko, stroking the small perfect handfuls of her breasts and tucking his fingers between her thighs, circling the tips of them around her clit and dipping them inside her while she takes deep, shuddering breaths against his shoulder and Teppei hums encouraging nonsense from where he is kneeling behind her. She hasn't come yet, Junpei is pretty sure of that, but she's soaking wet now and may be close enough that it makes no difference. Goodness knows that _he's_ going to lose his mind pretty soon if he has to stay here for very much longer, feeling the heat of Riko's body close but not close enough, and he groans with desperate hope when Riko finally, _finally_ says, "Come _on_, Teppei."

Teppei, who never changes no matter where he is or what he happens to be doing, just laughs. "All right." At least his voice is half an octave lower than usual, too, and his face flushed and eyes dark over Riko's shoulder when he shifts again, stroking his hands over Riko's hips. "You're the boss."

"Of course I am—_oh_." Junpei can't see her face when she has her forehead pressed against his shoulder like this, but he can hear the note in her voice, open and stunned to match the sound Teppei makes, and it matches the way Junpei always feels in that first moment of the hard stretch and pressure of Teppei sinking into him. "_Oh_..."

Teppei's eyes are closed and his lips are moving silently. Junpei will never, ever tell him that he's learned to read the syllables that Teppei tells over in these moments, like a man praying, syllables that make the words _I love you_ and _you are so good, you are so perfect_ and _never leave me_ and their names over and over again. It's not like Teppei tries to keep those things secret, not when they show in everything he does, but it might embarrass him to know how transparent it is here, like this.

The three of them still when Teppei finally comes to rest against Riko. She's trembling against Junpei's chest, panting softly, and Teppei is groaning deep in his throat, and Junpei can hardly breathe with how the two of them look together. For a moment, no one moves. Then Riko gasps, "Junpei, _now_," like a command.

Junpei groans with the relief of finally being able to move, to shift himself under her and let his cock sink into her, hot and tight around him. She moans and Teppei does too as even that small movement jostles them. At that point, even the idea of being able to hold a coherent thought together becomes a joke. There's only the movement of their bodies against one another, Teppei letting his hands roam over their bodies, insistently gentle as the way he moves against her, and Riko held between them, gasping and crying out by turns. She grinds down against Junpei's cock, her body flexing and holding them both as she comes, and again, and again, a long series of shudders shaking her. Or maybe it's one long shudder that just doesn't stop for as long as Junpei keeps rocking up against her, urgent with the pleasure singing along his every nerve, until he can't hold himself back any longer. When he hits that edge, it's hard enough that his vision actually whites out with the force of it, and all that he knows for an endless moment is heat and pleasure and the sounds they make, Riko's groan and the wordless, yearning sound Teppei makes as his hands tighten on them and he follows after them.

They're still a mess, all tangled together and breathing hard, sticky and sweaty and dazed, when Riko says, "Okay. I'm convinced."

Junpei lifts a hand to pet her hair, clumsily, too wrung out to be anything more than satisfied with that... until Teppei says, "But you haven't even tried it from the other side yet."

Riko makes a thoughtful sound. "You're right."

Junpei closes his eyes and groans. They are _definitely_ going to be the death of him.

(The secret he will never surrender is that he wouldn't have it any other way. But then again, they probably already know.)

**end**

Because after one pounds out forty thousand words of fraught fic, a porny chaser is in order. Comments are always lovely!


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